THE DEVELOPING ANTERIOR SKULL BASE - CT APPEARANCE FROM BIRTH TO 2 YEARS OF AGE

PURPOSE: To describe the normal CT appearance of the developing anteri or skull base in children 24 months of age and younger. METHODS: A ret rospective review of the CT examinations of a healthy population of 61 subjects newborn through 24 months of age was performed. Two investig ators independently reviewed the examinations, making measurements and observations regarding the length of the skull base, ossification pat tern, and development of the crista galli, perpendicular plate of the ethmoid bone, and fovea ethmoidalis. RESULTS: At birth, the anterior s kull base is largely cartilaginous. Ossification begins in the roof of the ethmoidal labyrinth laterally and spreads toward the midline. By 6 months of age, 50% of the anterior skull base has completely ossifie d. This percentage steadily increases over the first 2 years of life, and by 24 months, 84% of the anterior skull base is completely ossifie d, with a cartilaginous gap anteriorly in the region of the foramen ce cum, the residual unossified portion. Ossification of the crista galli and perpendicular plate of the ethmoid bone begins around 2 months of age, shows a steady increase in ossification to 14 months of age, the n increases little to 24 months of age. The fovea ethmoidalis begins d evelopment by 6 months of age, with the anterior portion the most deve loped in 82% of the population. CONCLUSION: The timing and pattern of ossification we observed differ somewhat from that reported in prior r adiologic and anatomic studies, with the earliest bony bridging of the ethmoidal complex to the crista galli seen as early as 2 months of ag e. Development of the anterior skull base follows a predictable and or derly pattern that is important for understanding how to avoid errors in interpreting CT examinations through this region.